The market for french fried potato strips, commonly referred to as french fries, is currently estimated at approximately 6.5-7 billion dollars annually. The bulk of this market is the fast-food restaurant business, wherein parfried and frozen potato strips are commonly purchased in bulk from commercial suppliers and stored at freezer temperatures until shortly before serving. At that point, the parfried and frozen potato strips are prepared for eating by deep fat frying in fat or oil.
McDonald's.TM. french fries, long considered the state of the art in the fast-food industry, apparently are processed according to the process disclosed in U.S. Pat. No. 3,397,993 (Strong). Therein, raw potato strips are blanched by steam or hot water until generally translucent throughout, dehydrated in hot air to cause a weight loss of at least 20 percent, parfried for 30-60 seconds at 375.degree. F. and then frozen to about 0.degree. F. The frozen potato strips are shipped and/or stored until final frying is desired. They are finish fried by immersing in a deep fat or oil bath, usually containing a medium consisting mainly of beef tallow, at a temperature of about 300.degree.-375.degree. F. for 1.5-3.5 minutes.
Another method for preparing french fries for fast food restaurants is taught in U.S. Pat. No. 3,649,305 (Wilder), wherein potato strips are dehydrated to reduce their moisture content by 10-30 percent, blanched, parfried for 30-90 seconds at about 300.degree.-400.degree. F. and then frozen. The frozen strips are then fried in oil for 1.5-3 minutes at 325.degree.-375.degree. F.
Many attempts have been made to duplicate for home use the flavor, aroma, color, texture and total eating experience of deep fat fried french fries prepared according to the above or similar methods. These efforts have met with varied results. The processes used in the prior art are pan-frying in oil or oven baking. To date, all of these prior art methods suffer from one or more deficiencies. For example, they produce limp, soggy, greasy, or dehydrated products which do not approximate the total eating experience of fast-food french fried potatoes. Examples of these prior art methods include those disclosed in U.S. Pat. No. 3,597,227, U.S. Pat. No. Re. 27,531 (Murray et al.), U.S. Pat. No. 3,865,964 (Kellermeier et al.), U.S. Pat. No. 3,751,268 (Van Patten et al.), U.S. Pat. No. 4,317,842 (El-Hag et al.), U.S. Pat. No. 4,551,340 (El-Hag et al.), U.S. Pat. No. 4,109,020 (Gorfien et al.), U.S. Pat. Nos. 4,456,624 and 4,559,232 (both to Glantz et al.), U.S. Pat. No. 4,632,838 (Doenges), U.S. Pat. No. 4,590,080 (Pinegar), U.S. Pat. No. 4,219,575 (Saunders et al.) and U.S. Pat. No. 4,272,553 (Bengtsson et al.).
U.S. Pat. No. 4,317,842 (El-Hag et al.), for instance, discloses a process for producing french fried potatoes which upon oven baking is intended to simulate deep fat fried potato strips. Raw potatoes are peeled, cut, parfried for 30-60 seconds at 375.degree. F. and then frozen. Thereafter, the parfried and frozen potato strips are coated with a 4 percent potato starch solution, soaked in an oil bath at a temperature of from 120.degree.-210.degree. F. for 2-6 minutes, and thereafter par-fried at 325.degree.-400.degree. F. for 10-250 seconds. The potato strips are then frozen and later oven baked, preferably using a special conductive heat transferring apparatus.
Another reference, U.S. Pat. No. 3,865,964 (Kellermeier) discloses a process for producing an oven baked french fried product by spraying edible oil or fat onto frozen potato strips, freezing the potato strips, and then baking the potato strips in an oven.
Methods such as those outlined above are deficient in that they require a special apparatus for final preparation, or require a significant time period (i.e., oven warming and baking) before the frozen product is ready to serve. In addition, the potato strips which are baked in an oven are exposed to significantly greater temperatures on their exterior than in their interior. Moreover, regardless of the oven temperature, the bottom of the potato strips which sit on the cooking pan, etc. are exposed to much greater temperatures due to conductive heating than the upper surface, which is heated mainly by convection. This causes the bottom surface to burn while the upper surface remains relatively moist. It has been difficult if not impossible to recreate the total eating experience obtained from deep-fat frying in the conventional oven found in most homes. Thus, these techniques are of limited value.
More recently, attention has been directed to the use of microwave ovens for preparing frozen french fries. In a microwave oven, high frequency energy is passed through the food product. The power absorption or specific absorption rate for a particular product depends upon a variety of physical and chemical factors, such as frequency, product temperature, the magnitude of the electric field in the product, density and dielectric constants. The high frequency energy excites polar molecules (such as water) contained within the food product and heat is generated as a result.
Various references disclose methods for preparing french fried potato products which can be cooked in microwave ovens.
U.S. Pat. No. 4,456,624 (Glantz et al.) discloses embedding potato pieces in potato strips by high energy impingement which disrupts the surface which has been preheated in water. Thereafter, the strips are blanched and parfried for 5-20 seconds at 340.degree.-380.degree. F. After freezing, the potato strips are by either fried or oven baked to complete the process. The patent also states that the potato strips also may be finally cooked in a microwave oven, although no examples are provided.
U.S. Pat. No. 4,590,080 (Pinegar) discloses subjecting potato strips to blanching, parfrying for 50-100 seconds at 360.degree. F., intermediate freezing at -40.degree. F. for 10 minutes, a longer parfrying for 2-4 minutes at 360.degree. F., blast freezing, storing and microwaving. The microwaving of a 3 ounce quantity of french fried potato strips is stated therein as requiring a 650 watt power setting for 1.5-2 minutes.
U.S. Pat. No. 4,109,020 (Gorfien et al.) discloses partially dehydrating frozen parfried potato strips by heating in an air oven or by heating in a combination microwave/air oven and then additionally heating in an air oven, frying in a deep fat fryer for 1 to 3 minutes at 375.degree. F., freezing at -10.degree. F. for 4 hours, storing and microwaving. The microwaving is at 650 watts for 135-180 seconds.
Finally, U.S. Pat. No. 4,219,575 (Saunders et al.) discloses a complex sinusoidal strip surface configuration for crinkle cut potatoes which are subjected to frying for 4 minutes at 350.degree. F., and thereafter blast frozen to an internal temperature of 0.degree. F. A two ounce sample exhibited increased crispness when heated in a microwave oven for one minute at 1000 watts.
Due to the large amount of water present in these prior art microwaveable potato strips, they are actually being cooked in the microwave oven rather than reheated. The heating caused by the action of microwave energy upon the aforementioned amounts of water within the potato strip often causes structural damage in the form of collapsed areas. Additionally, during microwaving, the moisture in the food piece is driven outward, which can cause the exterior to become soggy.
It is therefore an object of the present invention to provide a french fried product which when reheated in a conventional microwave oven, closely resembles the flavor, aroma, texture, mouthfeel and total eating experience of a deep-fat fried fast food french fry.
It is another object of the present invention to produce a product which utilizes the particular manner in which a microwave oven heats food products in order to provide a highly palatable french fried product which has a crisp exterior and a tender interior.
It is a further object of the present invention to provide a microwaveable french fried product which does not become soggy or limp upon heating and which does not suffer from the structural collapse present in prior art microwaved products.
It is yet another object of the present invention to provide a microwaved french fried potato product which can be reconstituted in a convenience store or in the consumer's home in a very short period of time, i.e., about one minute or less for an ordinary serving, and which is virtually indistinguishable from deep-fat fried french fried potatoes which may be purchased in fast-food restaurants.
It is yet another object of the present invention to provide a french fried potato product which can be reconstituted in a deep fat fryer in a very short period of time in comparison to prior art procedures, and which is virtually indistinguishable from deep fat french fried potatoes which may be purchased in fast-food restaurants.